Doping is a very effective strategy for tailoring the electronic band structure and improving the charge transport properties of WO₃, which could in turn enhance its photoelectrochemical (PEC) activity. In this work, we report a facile hydrothermal route to synthesize Bi doped WO₃ thin films on fluoride-doped tin oxide (FTO) glass substrate and investigated the insights of its band alignment. Systematic doping of Bi into WO₃ was achieved during the condensation of peroxopolytungstic acid (PTA) in the course of hydrothermal synthesis. The effect of Bi doping on the morphology and crystal structure was investigated and the approximate amount of Bi incorporated into WO₃ was estimated using energy dispersive spectroscopy (EDS). Results of UV–Vis spectroscopy, Mott-Schottky analysis and valence-band (VB) X-ray photoelectron spectroscopy revealed that the insertion of Bi into the lattice of WO₃ changes the band gap, valence band maximum, and the conduction band minimum of WO₃. PEC measurements displayed remarkable enhancement in photocurrent values from 0.401 mA cm⁻² for un-doped WO₃ to ∼1.511 mA cm⁻² (ca. 4-fold increase) for optimized Bi doped WO₃ samples at 1.23 V vs. RHE under simulated AM 1.5 G sunlight without the addition of catalysts. The results of electrochemical impedance spectroscopy confirmed that doping WO₃ with Bi lead to low charge transfer resistance across the electrode/electrolyte interface and an increase in charge-carrier density. This work suggests that Bi doping has the potential to significantly improve the PEC water splitting efficiency of WO₃.

掺杂是一种非常有效的策略，可用于调整电子能带结构并改善WO ₃的电荷传输性能，从而可以提高其光电化学（PEC）活性。在这项工作中，我们报告了在掺氟的氧化锡（FTO）玻璃基板上合成Bi掺杂的WO ₃薄膜的便捷水热路线，并研究了其能带排列的见解。在水热合成过程中过氧聚钨酸（PTA）的缩合过程中，将Bi全身性地掺杂到WO ₃中。研究了Bi掺杂对形貌和晶体结构的影响，并向WO _3中掺入了大约Bi的量。使用能量色散光谱法（EDS）估算。UV-Vis光谱，Mott-Schottky分析和价带（VB）X射线光电子能谱的结果表明，将Bi插入WO ₃的晶格会改变带隙，价带最大值和导带最小值。 WO ₃。PEC测量显示光电流值显着提高，从未掺杂的WO _3的0.401 mA cm ^-2到优化的Bi掺杂的WO ₃样品在1.23 V vs. RHE下的模拟电流下，约为1.511 mA cm ^-2（约增加4倍），在模拟下在不添加催化剂的情况下，AM 1.5 G阳光下。电化学阻抗谱的结果证实了掺杂WO具有Bi的图₃的电极导致跨电极/电解质界面的低电荷转移电阻，并且电荷载流子密度增加。这项工作表明，Bi掺杂具有显着提高WO ₃的PEC水分解效率的潜力。